From reading FT, the general consensus is that the new VS premium economy is much better than BA's WTP. Personally I would pocket the 200 GBP and take VS. The Club House at least in 1 direction is going to be much better than the BA F lounge as even most die hard BA fans will admit. If you have a PP membership, I'm sure there is a lounge in DEL you can access on your way back. Don't forget VS move out of T3 soon so this is a good opportunity to give it a try!

If your potentially short on tier points for requalification, I would go BA.......... then again I'm sure that does not apply here!